Question

A ball is dropped downward from the roof of a building and simultaneously another ball is thrown in a horizontal direction, when will the balls reach the ground?

(a) Same time and same place

(b) The first ball will reach later than the second ball

(c) The second ball will reach later than the second ball

(d) Same time but different places

I got this question in an international level competition.

Query is from Motion in a Plane in section Laws of Motion of Engineering Physics I

Answer 1

Right choice is (d) Same time but different places

To elaborate: Both the balls will reach the ground at the same time but at different places. The vertical motion is not affected by the horizontal motion. This is called the principle of physical independence.